The Red-throated Diver's calls are desolate and unforgettable. In the song flight and at the breeding pool, plaintive, wailing "aa-oo" cries and whining, cackling sequences are heard that carry far over silent woodlands and bogs. The calls are given above all at dusk and dawn in May–June. A lone Red-throated Diver calling at its pool on an early June morning is among the most powerful experiences of nature in the Swedish forest landscape.